In humans, as in laboratory animals, a busy mental lifestyle keeps
the mind fit, says Schaie, now director of the gerontology center in the
College of Human Development at Penn State. "People intensely involved in
life retain their intellectual abilities better than mental couch
potatoes." The conclusion may sound cliched, but it's drawn from the test
scores of serious bridge players and crossword-puzzle fanatics. Their
cognition decreases less with age than that of people whose most
challenging pastime is bingo.
"A person who stops solving problems arrives at a point where he
can't solve problems," Schaie declares.
Generally, people who develop chronic diseases after age 50
function less well mentally than they did before they became ill. In his
studies, Schaie detected a decline in mental function among individuals
who underwent lengthy hospitalizations for cancer, heart disease, or
other chronic illness. The loss, however, was modest, suggesting it was
not the direct effect of disease. He postulated it might be due to the
passivity and mental indolence encouraged by hospital routine.
Schaie's wife and colleague, Sherry Willis, Ph.D., tested this idea
by giving puzzlelike assignments in problem-solving and reasoning to a
group of long-term hospital patients over age 65, then coached them in
mental strategies and short cuts. Their cognition improved. Seven years
later, they retain their renewed mental vigor.
Cognitive style, the third factor in maintaining mental function,
is what Schaie calls "the ability to adapt and roll with life's punches."
He measures mental rigidity and flexibility with questions ("Do you
insist on having a place for everything and everything in its place?")
and tests requiring people to perform familiar tasks in an offbeat way.
For example, he will ask people to copy a paragraph substituting
uppercase letters for lowercase ones.
"These tests seem silly, but flexible-minded people manage to
complete them," says Schaie. "They laugh. The rigid person responds with
tension and dithering instead, forcing himself through the exercise and
performing poorly." Those who score highly on tests of cognition at an
advanced age are those who tested high in mental flexibility at middle
age.
GETTING OLDER, GETTING BETTER
The great individual variability in tests of mental function that
shows up as people age suggests something crucial: major deterioration is
not preordained by nature. Substantial decline is not necessarily built
into the brain. What commonly occurs must not be interpreted as
inevitable.
Every psychologist knows that as we live our unique histories we
develop in increasingly divergent ways. No doubt, we're building our own
customized assortment of neural networks.
Between birth and maturity, the brain triples its weight although
vast numbers of brain cells die. During the first year of life this cell
decline is so dramatic that any later cell losses look trivial by
comparison. But, under the influence of stimulation and education, the
surviving brain cells go forth and multiply their connections. They
develop increasingly elaborate networks of dendrites with which to
communicate with each other. Hard data from a number of labs suggest that
in a healthy brain, whenever one cell is lost, its neighbors respond by
adding dendrites, assuming the work of the lost cell.
As the number of dendrites grows, messages move across synapses
along increasingly elaborate and interconnected pathways. Repeated mental
activity forges the most direct routes, driving the brain to become both
more efficient and more versatile overall.
With its ability to adapt as new information comes in, the mind has
a built-in capacity for self-improvement throughout life. From the
beginning, the systems we use are the ones that are favored, and those
that seem functionally superfluous are discarded. Once mental abilities
are fully developed, the mind functions with increasing strategic
efficiency, like computer programs that debug themselves.
Skills improve as new strategies and short cuts are learned; the
grade school child's laborious pencil-and-paper or finger-counting
process of adding 26 and 12 becomes a computation most adults can do in
their heads.
"If you ask really little kids to add two and two, they'll hold out
two fingers, then two more, and count them," observes Purdue's Robert
Kail. "Counting is accurate but inefficient. Slightly older children
don't use their fingers, but they're counting imaginary ones. Seven- or
eight-year-olds retrieve the sum from memory. They've begun to learn it's
more efficient to have some basic information ready all the time."
A 12-year-old, asked to multiply 5 times 8, might misremember the
product as 42. But then he'd think about it. If he felt unsure, he'd try
another way, perhaps adding five 8s together. If he didn't get an answer
he felt confident about, he'd try a third method, test his confidence in
the answer, and so on. This "strategy-choice model" is the foundation of
flowcharts, computer programs, common sense--and it may improve with
time.
Once the mind attains its adult level, it goes through these steps
automatically. When you're posed a problem requiring an answer, you first
check your memory. if you find something that looks like what you want,
you check it, test your confidence, and, if you're not sure, go to a
backup strategy and test that result.
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